A police chief has defended officers after a video showing them embroiled in a heated exchange over a stop and search procedure went viral.

Metropolitan Police commander Simon Letchford took the unusual step of issuing a lengthy account of the police response after footage of the incident in South Norwood in south-east London was uploaded to Facebook then seen by more than a million people.

The clip shows a man angrily arguing with a group of officers while they search his bag after it was suspected he may be dealing drugs to youngsters.

But it was soon discovered he had no drugs and was just reaching into his bag to get money for his daughter to buy sweets.

In the footage, which was filmed by the man's friend Adrian Medford, a large crowd can be seen and shouts of "racist" and "no reason" can be heard.

Mr Medford, 34, from Croydon told the BBC that he was outside his home on April 16 when a friend he was with was stopped, searched and handcuffed.

He said the friend had a bag and that he had "reached into it and gave 50p to his daughter so she could go buy sweets".

Mr Medford said he filmed the incident and uploaded it because he thought the police "were totally out of order". It has been viewed more than 1.1 million times on Facebook.

Now Mr Letchford has been forced to defend the move using a Scotland Yard blog post.

He said two local officers attended the scene after a member of the public called police to report their belief that drugs were being sold to young people on the high street.

The commander said: "The man was handcuffed and moved away so the search could be conducted away from the crowd but he was not arrested and he was not taken to a police station. "

No drugs were found, the man was released and the crowd dispersed, Mr Letchford said and added: "there is a fair amount of abuse directed at the officers".

He said that because the incident was filmed and uploaded to social media, more than one million people have seen it "without the background knowledge that it all started with a credible call from a concerned member of the public that they thought drugs were being sold to young people in their community".

Having watched the film, he said he has "no reason to be concerned about how the officers acted", adding: "The situation became difficult but they did what they needed to do in a fair and proportionate manner, considering the information they had."

He rejected suggestions that the exchange echoed the situation in the US city of Baltimore, where relations between police and the community have threatened to unravel in recent weeks.

"Of course tensions between the police and public are a concern and there is more to be done, but I am also proud of the progress we have made," Mr Letchford said. "Hopefully blog posts like this go someway to explaining why we need to police the city the way we do."

He added: "There is no easy answer when it comes to difficult policing decisions. However, I welcome scrutiny and when we get it wrong - and I don't think we did here - then we will be judged on how we respond.

"I just hope that what is viewed by the public on social media is done so with context and as many facts as possible."